The interactions between Ostertagia ostertagi and Cooperia oncophora were studied in calves by concurrent and sequential infections. A reciprocal negative interaction between the 2 species was found in sequential, but not in concurrent infections. This result was supported by the finding of serological cross-reactions. It is suggested that the negative… (More)

A number of haematological parameters were monitored in eight-month-old Merino wethers, six infected with 10,000 Haemonchus contortus and 13 controls. Blood loss caused by infection was reflected in a decrease in packed cell volume (r = -0.78; P less than 0.001), and was correlated with faecal egg excretion (r = 0.89; P less than 0.001). Infected animals… (More)

A recently isolated field strain of Haemonchus contortus was passaged through resistant (repeatedly reinfected) and susceptible (immunosuppressed) sheep for six and nine generations, respectively. Infectivity of the resulting serially passaged strains was not significantly different when tested in groups of 1-year-old susceptible sheep.

The major histocompatibility (B) complex of a distinct commercial pure White Leghorn chicken line was characterized using serological, biochemical and restriction fragment length polymorphism (RFLP) typing. Line B chickens displayed a high recombination frequency within the B complex. Three recombinant haplotypes were identified. The influence of these… (More)

1. The relationship between the length of incubation, hatching, hypoxic condition, thyroid hormones and the occurrence of ascites were studied in embryos of 2 broiler lines differing in susceptibility to the ascites syndrome. 2. Both the time of external pipping (ep) and hatching of embryos from the ascites-resistant (AR) broiler line was earlier compared… (More)

Over a period of nine years, ten experiments were conducted on Cooperia oncophora infections in calves. A total of 327 calves were infected, each with a single dose of 100 000 infective larvae. The large variation between experiments in the faecal egg output of calves appeared to be related to the time of year at infection. Calves infected in the Spring… (More)